I'd say that's a "yes and no" proposition. If you know there's a major game changer coming within a *reasonable* amount of time, it's often better to wait a bit-- and typically you know about the game changers a bit in advance.
Sandy Bridge was a good example therein, though it was hampered by serious problems with the launch.
Nothing sucks like buying a motherboard right before the socket and/or RAM type gets obsoleted.